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Spermatogenesis in the golden hamster: the role of c-kit
M Vigodner1, L M Lewin, L Shochat
1Department of Clinical Biochemistry, Sackler Medical School, Tel Aviv University, Ramat Aviv, Israel. margarit@post.tau.ac.il
Abstract:
c-kit is related to the family of transmembrane tyrosine kinase receptors. Mutations in genes for either c-kit or its ligand, Steel factor, result in infertility, but the role of c-kit/SCF system in spermatogenesis is not well understood. In this study Western blot analysis together with confocal microscopy were used to follow c-kit expression in hamsters during the first spermatogenic wave in mature animals and in old age. Three antibodies raised against different domains of c-kit were tested on Western Blot. Confocal microscopy was performed after incubation of fixed seminiferous tubules with tested antibodies followed by binding of FITC-labeled secondary antibody. Longitudinal sections of seminiferous tubule were observed by confocal microscopy to determine in which stages of spermatogenesis and in which cell types c-kit was found. C-kit bands of 80,140, and 150 kDa were observed on Western blot, indicating that c-kit is a name related to several proteins sharing some common domains. Only the band of 150 kDa correlated with positive staining of c-kit in tubules using confocal microscopy. We term this protein c-kit150T (150 kDa, testis). We demonstrated that c-kit150T appeared in differentiating hamster spermatogonia at stages VII-VIII of adult spermatogenesis and at day 13-14 during the first spermatogenic wave. It remained attached to the cell until late pachytene. This suggests that c-kit may play a role in preparing the germinal cells to enter meiosis. In order to evaluate the effect of aging on the number of germ cells, B2 spermatogonia/Sertoli cell ratio was calculated in the group of young animals (5-7 months) compared to this ratio in older ones (20-26 months). A significant decrease (P < 0.01) in the number of B2 spermatogonia in the group of old hamsters as compared to young ones was seen. The calculated value for the B2 spermatogonia/Sertoli cell ratio was 5.6 +/- 0.7 in young animals and 3.8 +/- 1.2 in the 20-26 months ones. In addition, decrease in the intensity of staining for c-kit was detected in the old hamsters. These may be the reasons for subfertility in old age and in other cases of testicular disorders.
Insights
The c-kit receptor tyrosine kinase, specifically the c-kit150T protein, is crucial for spermatogonia development during spermatogenesis. Aging reduces c-kit150T expression and germ cell numbers, potentially causing subfertility.
Area of Science:
- Reproductive Biology
- Cell Signaling
- Molecular Endocrinology
Background:
- The c-kit receptor tyrosine kinase and its ligand, Steel Factor, are implicated in infertility, but their precise role in spermatogenesis remains unclear.
- Understanding c-kit expression patterns is vital for deciphering male reproductive processes and age-related fertility decline.
Purpose of the Study:
- To investigate the expression of c-kit during hamster spermatogenesis in mature and aged animals.
- To identify the specific c-kit protein isoform involved in spermatogenesis and its cellular localization.
Main Methods:
- Western blot analysis to detect c-kit protein bands.
- Confocal microscopy to visualize c-kit localization in seminiferous tubules.
- Quantification of B2 spermatogonia to Sertoli cell ratio in young versus aged hamsters.
Main Results:
- A 150 kDa c-kit protein, termed c-kit150T, was identified and localized to differentiating spermatogonia.
- c-kit150T expression was observed during specific stages (VII-VIII) of spermatogenesis and the first wave.
- A significant decrease in B2 spermatogonia and reduced c-kit staining intensity were noted in aged hamsters.
Conclusions:
- c-kit150T plays a role in germ cell differentiation and preparation for meiosis.
- Age-related decline in c-kit150T expression and germ cell numbers may contribute to subfertility in older hamsters.
- This study highlights c-kit's importance in maintaining male reproductive function throughout life.